Circuit Research Labs, Inc.

Cardio Theater

Stan Sasaki

Forrest Scott Seitz

Eric B Lane

An echo suppressor uses a multi-state operating sequence to provide non-disruptive monitoring of a remotely broadcast program during a performer's live performance at a local site. The operating sequence is actuated by a voice activated switch that initiates signal processing for correlating a locally originating audio (e.g., the performer's voice) to its echo in the broadcast program. During correlation states in the operating sequence, the echo suppressor switches monitoring to a local microphone signal to allow the performer to hear his or her own voice while preventing echo from being heard before correlation is achieved and echo suppression can begin. The correlation states include an initial correlation at a reduced sampling rate to detect echo within a wide delay time window and determine the locally originating audio is on-the-air. A subsequent state then performs a second correlation at a higher sampling rate to correlate to the echo in a narrower delay time window displaced according to the approximate delay determined in the initial correlation.

Multi-state echo suppressor

A receiver in an audio distribution system provides graceful degradation of audio quality as transmission quality decreases by dynamically adjusting the volume of audio output as a function of transmission quality. The receiver estimates the rate of transmission errors in a transmission link on which the audio signal is distributed by detecting errors in known information embedded in the audio signal. As the rate of transmission errors increases, the receiver increasingly attenuates the volume of the audio output. The receiver dynamically adjusts the volume relative to the rate of transmission errors applying a smoothing function to avoid disruptive rapid fluctuations in audio output volume.

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Lake Oswego, OR, United States of America

Stan Sasaki